Republicans know they’ll need every last dollar in next year’s campaign if they want to keep Democrats from topping 60 seats in the Senate.

So with potentially better Senate investments on the horizon, is it worth continuing to pour money into Norm Coleman’s long-shot Senate campaign if the race keeps going on and on?

GOP senators, the Republican National Committee and the National Republican Senatorial Committee insist that the Coleman challenge has been worth the money — for now. Over the past three months, the NRSC spent nearly $1 million to pay his legal bills, and since Election Day, Republican senators and the RNC have pumped in hundreds of thousands of dollars more. Last Thursday, the Federal Election Commission opened the door for Coleman to use campaign cash to defend himself in two lawsuits unrelated to the current recount battle — putting the former senator in the position of asking his GOP donors to pick up more of his hefty legal tab.

Coleman’s legal challenge has reached the Minnesota Supreme Court, but many legal experts believe that the court’s decision — expected any day — will affirm that Franken won last November’s election. If that happens, Coleman will have a choice: concede and allow Al Franken to become the 60th Democratic senator or take his court fight to the federal level, a move that would almost certainly force the GOP to reach deeper into its pockets to keep fighting a 2008 race while every other campaign committee has moved on exclusively to 2010 fundraising.

And 2010 hasn’t yet emerged as a particularly smooth ride for the Republican Party. The GOP has 18 seats to defend, including five retirements, and the party continues to suffer from dismal approval ratings. Two of the party’s rising stars — Sen. John Ensign of Nevada and South Carolina Gov. Mark Sanford — have been laid low by sex scandals, further harming the party’s national image.

By continuing to support Coleman’s bleak chances ahead of a bruising election year, Democrats gleefully think that the GOP is wasting precious 2010 resources.

“Given the 2010 map, sooner or later Republican incumbents will question the strategy of sending $1 million to a race they lost seven months ago,” said Eric Schultz, spokesman for the Democratic Senatorial Campaign Committee.

But Sen. John Cornyn (R-Texas), chairman of the National Republican Senatorial Committee, insists the Coleman challenge is money well-spent, and it won’t hurt his 2010 coffers.

“I don’t think it’s a factor on 2010,” Cornyn told POLITICO. “Norm has been raising a bunch of his own money, and the RNC and the NRSC [have] been helping some too.”

Of course, Cornyn and the GOP may not have to pay out much more for Coleman. There is an increasing expectation within GOP circles in Washington and Minnesota that Coleman is going to call it quits if he loses before the state Supreme Court, even though sources in Coleman’s camp insist he won’t make up his mind until he sees the court’s decision.

Democrats have so far put less money into the Minnesota recount. Since Election Day, the DSCC has raised $282,000 for Franken, compared with about $441,000 the NRSC raised for Coleman. And the NRSC spent more than $996,000 in legal bills in April, May and June, including a $300,000 check it cut for the recount fund in May. The NRSC has been helped, too, by the RNC, which gave the senatorial committee an additional $1 million last month.

Cornyn, who views the race as his first battle since assuming the NRSC chairmanship after the November elections, has the backing of GOP senators who have helped contribute $336,000 to Coleman’s effort since Election Day, according to FEC reports.

“If you say ‘Well, you can pick up a seat in Minnesota for an extra million dollars’ — that’s a real bargain,” said Sen. Bob Bennett (R-Utah), who is up for reelection in 2010.

Sen. Lindsey Graham (R-S.C.) said he had no qualms donating money to Coleman’s cause — and he says he’ll keep backing Coleman even if he takes the case to either the U.S. Supreme Court or federal district court.

“I’m going to back Norm whatever he does,” Graham said.

“It’s a great American tradition if you got one sailor lost in the sea, you send the entire Navy to go find him,” said Sen. Lamar Alexander (R-Tenn.), the chairman of the Senate Republican Conference. “So we’re making a special effort to try to make sure every vote is counted and that if Norm Coleman has a chance to win, that he’s back here in the Senate.”

Including the recount, the entire race has cost an estimated $50 million, including at least $13 million since Election Day. And both Franken and Coleman have raised money frantically to ensure their legal bills are paid.

But even as he pushes his recount challenge into its eighth month, Coleman faces other sticky legal problems unrelated to his election. He’s monitoring two lawsuits alleging that a longtime associate, Nasser Kazeminy, improperly steered some $100,000 to Coleman through his wife’s place of employment.

Coleman has denied any wrongdoing, calling the suits politically motivated — and senators who have donated to Coleman’s cause don’t seem to have an issue with him spending money to deal with those legal bills, as well.

“I don’t have a problem with it — I think it’s all related back to the campaign,” said South Dakota Sen. John Thune, No. 4 in the Republican leadership, who gave Coleman $5,000 earlier this year. “It’s part of the campaign that was leveled against him last fall, all of which I think was drummed up and hyped, which I think, when the facts come out, will be completely refuted.”

Sen. Bob Corker (R-Tenn.), who donated $5,000 to Coleman’s cause in February, said Coleman “should have the freedom within the context of our contribution to do those things he feels are necessary.”